Innate Immunity Overview

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Questions and Answers

What is the primary role of circulating effector proteins in innate immunity?

To solely promote inflammation

To produce antibodies against pathogens

To enhance the adaptive immune response

To inhibit the growth and promote the destruction of microbes (correct)

Which of the following is not classified as a circulating effector protein?

Neutrophil (correct)

Interferon

Lysozyme

C-reactive protein (CRP)

What type of cells are primarily responsible for phagocytosis?

B cells

Epithelial cells

Phagocytes (correct)

Natural killer cells

How do acute phase proteins, such as C-reactive protein, contribute to immune defense?

By enhancing host resistance and repair Signup and view all the answers

Which of the following correctly describes the action of lysozyme in innate immunity?

It lysis bacteria by breaking down their cell walls Signup and view all the answers

Which of the following describes the role of natural killer (NK) cells in innate immunity?

They identify and destroy infected or cancerous cells Signup and view all the answers

What triggers the process of chemotaxis in phagocytosis?

Chemotactic substances from microbes and damaged tissues Signup and view all the answers

Which of the following is false regarding the cells of innate immunity?

Natural killer cells are a type of phagocyte Signup and view all the answers

What mechanism allows the attachment of phagocytes to pathogens?

Pathogen recognition receptors (PRRs) Signup and view all the answers

Which of the following statements best describes opsonization?

The process of pathogen coating by antibodies or complement proteins. Signup and view all the answers

Which substances are produced by activated macrophages to kill phagocytosed microorganisms?

Oxygen radicals and lysozyme Signup and view all the answers

Natural killer (NK) cells primarily function in which aspect of immunity?

Non-specific cytotoxic activity Signup and view all the answers

What is the primary role of lysozyme in innate immunity?

Destruction of bacterial cell walls Signup and view all the answers

What process describes the movement of leukocytes through the endothelium to reach tissues?

Diapedesis Signup and view all the answers

Which of the following correctly identifies a component of the oxygen-independent killing mechanism?

Lysosomal enzymes Signup and view all the answers

Which component is primarily recognized by PRRs on phagocytes?

Microbial molecular structures Signup and view all the answers

What is one of the primary functions of pro-inflammatory cytokines such as IL-1 and TNF-𝛼?

To enhance the activity of neutrophils and macrophages. Signup and view all the answers

In what condition do acute phase proteins primarily function during the inflammatory response?

To signal immune cell activity. Signup and view all the answers

What type of barriers serve as the first line of defense in the immune system?

Physical and chemical barriers. Signup and view all the answers

How does nutritional status affect susceptibility to diseases?

Under-nutrition can increase the susceptibility to infections. Signup and view all the answers

Which of the following factors may modify an individual's innate immunity?

Genetic makeup. Signup and view all the answers

What role do phagocytes play in the inflammatory response?

They engulf bacteria and release enzymes to destroy them. Signup and view all the answers

Which statement accurately describes the role of normal microbiota in immunity?

They create physical barriers against pathogens. Signup and view all the answers

Which physiological change occurs as part of the inflammatory response?

Increased tissue temperature. Signup and view all the answers

Study Notes

Innate Immunity

Innate immunity is a natural, inborn barrier against microorganisms.
Its primary function is to prevent or limit infections by bacteria, viruses, fungi, and parasites.
This defense is performed by various cellular and humoral components interacting to coordinate an immune response that eliminates pathogens or minimizes damage.
Innate immunity acts as a first line of defense against infectious agents, checking them before they cause significant infection.

Objectives

Defining immunity and the immune system's two main components.
Identifying the first defense line of innate immunity.
Identifying the second defense line of innate immunity.
Understanding phagocytosis and its stages.
Defining opsonization.

Types of Immunity

The immune system consists of innate and adaptive immunity, working together.
Innate immunity, the first line of defense, is non-specific.
Adaptive immunity is called upon if innate defenses fail; it targets specific pathogens.

Components of Innate Immunity

First Line of Natural Defense:
- Mechanical barriers (intact skin, mucous membranes, hair in nares, coughing, sneezing, and blinking reflex/tears).
- Chemical barriers (sweat, sebaceous secretions, lysozyme, acidic pH).
- The normal microbiota (which suppress the growth of pathogenic bacteria and fungi).
Second Line of Natural Defense
- Circulating effector proteins (lysosome, complement, acute phase proteins, interferons).
- Cells of innate immunity (phagocytes, natural killer (NK) cells)
- Inflammatory barriers

Cells of the Immune System

The immune system's cells originate from stem cells.
The stem cells differentiate into lymphoid stem cells and myeloid progenitor cells, resulting in diverse cell types (B cells, T cells, natural killer cells, neutrophils, macrophages dendritic cells etc.).

Phagocytosis

Phagocytes (i.e., macrophages and neutrophils) are specialized for capturing, engulfing, and destroying invading microorganisms.
The process of phagocytosis involves chemotaxis and migration, attachment, ingestion, and intracellular killing or digestion.
Killing or digestion occurs via oxygen dependent pathways (radical oxygen production) or oxygen independent pathways using enzymes.

Opsonization

Enhanced Attachment and ingestion of organisms, coating microbes with opsonins (antibodies and complement).
Opsonization is the process of coating an organism to enhance phagocytosis.
It's aided by activated complement C3b or antibodies.

Natural Killer (NK) Cells

Large granular lymphocytes with non-specific cytotoxic activity against tumor cells, virus-infected cells, and graft cells.
They are essential to innate immunity.

Inflammatory Barriers

Includes vasodilation, increased capillary permeability, and fluid/cell influx into tissues.
Characterized by redness, increased temperature, swelling (edema), and influx of phagocytes into tissues.
Initiated by chemical mediators (released from damaged tissues or microbes, by plasma-enzyme systems, or by leucocytes).

Cytokines in Innate Immunity

Cytokines like IL-1, IL-6, IL-8, and TNF-α are crucial pro-inflammatory cytokines in innate immunity.

Constitutional Factors Affecting Immunity

Differences in species susceptibility to pathogens
Racial variations in susceptibility.
Genetic variations in individuals within the same race.
Age differences impacting immune system development and function (immaturity in children versus aging).
Nutritional status affects immunity (under-nutrition reduces immunity).
Hormonal influences and corticosteroids decrease immune response.
Specific examples include diabetics being more susceptible to infections.

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Description

Explore the essential concepts of innate immunity, the body's first line of defense against pathogens. This quiz covers the definition, key components, and functions of innate immunity, including phagocytosis and opsonization. Test your knowledge on how innate immunity interacts with adaptive immunity to protect against infections.